Company gets approval from US airline regulator to start testing redesigned battery for 787 Dreamliner planes.

The Dreamliner has been grounded worldwide since January after two battery failures [Reuters]

The US airline regulator has approved a plan by aircraft manufacturer, Boeing, to redesign the fire-plagued lithium-ion batteries for the 787 Dreamliner, but it has to pass a series of tests before the airliner can return to service.

The Federal Aviation Administration (FAA) approved the plan on Tuesday, which included changes to the internal battery components to avoid overheating.

Boeing's new battery - which it presented to the FAA in February - is designed to minimise the chances of a shortcircuit, insulates the cells within the battery better and adds a new containment and venting system to prevent damage even if the battery catches fire.

Flight tests of only two 787s with new battery prototypes have been approved so far by the FAA.

"This comprehensive series of tests will show us whether the proposed battery improvements will work as designed," Ray LaHood, the US transportation secretary, said.

"We won't allow the plane to return to service unless we're satisfied that the new design ensures the safety of the aircraft and its passengers."

'Welcome milestone'

The agency also said that the plan is an outline for a recertification of the plane's batteries, which has two identical lithium-ion batteries.

Boeing welcomed the decision.

"Today's approval from the FAA is a critical and welcome milestone toward getting the fleet flying again and continuing to deliver on the promise of the 787," Jim McNerney, Boeing chief executive, said in a statement.

The 787 fleet worldwide has been grounded by the FAA and civil aviation authorities in other countries since January 16, after two battery failures in Boston, US, and Japan.

The 787 is Boeing's newest and most technologically advanced plane. Its grounding marked the first time since 1979 that FAA had ordered every plane of a particular type to stay out of the air for safety reasons.